Questions & Answers

  1. 1
    Should I fit a spark arrestor?
    No. The fitting of spark arrestors is not recommended because the mesh has a tendency to become blocked by soot and tar, and can be difficult to clean. In this condition they are likely to increase the risk of chimney fires. But we always advise to confirm these details with your insurer before proceeding with any actions.
  2. 2
    What is the recommended chimney height above the thatch?
    Current building regulations say the minimum height is 1.8m 
  3. 3
    Is my chimney lined?
    If you don’t know, then we recommend that you contact your local HETAS approved engineer to complete a chimney survey and make the required recommendations. Find out more… 
  4. 4
    How long does a thatched roof last?
    The life of thatch will depend on a number of factors which include the pitch and design of the roof, type and quality of material used, geographical location, and degree of skill exercised by the Thatcher. In ideal circumstances thatched roofs have been recorded to last in excess of 100 years but under normal conditions the following approximate life expectancies can be used as a guide:

    • Water Reed                                        30-50 years
    • Combed Wheat Reed                         20-30 years
    • Long Straw                                         15-25 years
  5. 5
    How long does a ridge last?
    Depending upon the style of construction and type of material that is used, ridges can normally be expected to last between 10-15 years. 
  6. 6
    How do I identify what material is on my roof?
     Not easy to define but the following generalisations may give a clue:

    Water Reed

    • Even dense coat showing butt ends of material only
    • Likely to be angular in overall appearance with eaves dressed into place, ends of material at right angles to the stem
    • Likely to have a ‘block’ ridge
    • Likely to have wire netting on the ridge only

    Wheat Reed

    • Even dense coat showing butt ends of material only
    • Likely to be softer and more rounded in appearance with eaves cut into shape leaving an angled quill like end to the straws
    • Likely to be totally covered with wire netting

    Long Straw

    • Less dense and more ‘shaggy’ appearance to coat, may show a mix of butts and ears
    • Soft contours to the roof, especially windows
    • Should have a continuous line of hazel rod running on the surface at eaves and gables
    • These are called ‘liggers’ they may appear as two lines with cross-sparring between them

    NB: Be cautious, thatching materials are not easy to identify and there are many traps for the unwary.

  7. 7
    Does my roof have a fire barrier?
    If you can access your roof void safely, look between the rafters at the underside of the thatch. If you can see the thatch you do not have a fire barrier. If you can see a sheet or board material you may have a fire barrier. Try to establish whether this material is a bituminous or other type of sarking felt which does not constitute a fire barrier or it may be a fibre cement boarding or shiny flexible material which could be a fire barrier. 
  8. 8
    What fire retardants are available?
    Please review the Fire Barriers & Systems section of the website. 
  9. 9
    What does it cost to re-thatch a roof?
    Approximately £100.00 – £125.00 + VAT per m² of roof area including overhanging of eaves and gables (excluding scaffolding). 
  10. 10
    How thick is thatch?
    A single coat or thickness of thatch is normally between 300mm and 350mm. This thickness will reduce through the life of the roof as the result of natural erosion. 
  11. 11
    Why do some roofs have wire netting?
    Wire netting is fitted to thatch to prevent or reduce damage from birds or other vermin. Ridges are netted in most cases, as are roofs of Long Straw and Combed Wheat Reed. It is common practice to leave Water Reed without netting because it is more resistant to vermin damage. 
  12. 12
    How does thatch stay on the roof?
    Thatch is either fixed directly to the roof timbers with steel ‘crooks’ or screw fixings, or it is fixed to an underlying coat with hazel ‘spars’ which are twisted to form a staple which is driven through the new thatch into the old beneath. 
  13. 13
    How long does it take to thatch a roof?
    Dependent upon the size of roof and number of thatchers. A family sized four-bedroom, detached house would probably take a team of three men about one month. 
  14. 14
    Does strong wind affect a thatch roof?
    Under normal conditions a thatched roof, which is in good condition, is surprisingly resistant to high winds. The gale of the late 1980′s proved this to be the case. 
  15. 15
    How do I choose a Thatcher?
    • Select a thatcher via the ‘Find a Thatcher’ section on the TAS website.
    • Select a member of the National Society of Master Thatcher’s.
    • Select a member of one of the county associations.
    • Check they have in place the necessary insurance
    • Ask for references or to see examples of work.
  16. 16
    How do Thatchers price a job?

    By means of accurate measurements which is cross referenced with appropriate specifications and market rates prevailing in the area.

    NB: Measurements should always allow for the thickness at eaves, gables and ridge.

  17. 17
    Is there an added fire risk to thatch?
    According to statistics, the incidence of fire in thatched properties is no higher than any other type of roofing materials, but it is likely to cause greater damage. This may reflect the caution which is exercised by thatched property owners. Find out more… 
  18. 18
    Does my insurance premium come down if I have a fire retardant or a fire barrier fitted?
    Some insurers will offer a discount in these circumstances, please check with your provider. 
  19. 19
    Can I install a Velux window?
    Velux windows are relatively easy to install in a new roof i.e. prior to thatching. They are less easy to retro-fit in an existing roof but it is usually possible, with the help of a thatcher. See Roof Construction Detail for more information. 
  20. 20
    What pitch should my roof be?
    It is advisable to set the pitch at about 50°, dormer windows and eave windows should be at least at a 45° pitch, 45° is normally accepted as the minimum pitch at which thatch will perform effectively. 
  21. 21
    What is the Dorset Model?

    The Dorset Model is a set of guidelines to advise you of certain requirements if you are considering extending or constructing a new thatched roof building less than 12m from your boundary. Find out more about the Dorset Model…

For any other questions you would like answered please feel free to contact our office using the information detailed on our contact page.